Poly(thieno[3,4-b]thiophene)s from Three Symmetrical Thieno[3,4-b]thiophene Dimers

Abstract

Herein we report the synthesis of symmetrical bis(thieno[3,4-b]thiophene)s and their electrochemical polymerization. The 2,2‘-bis(T34bT) has an oxidation peak at 0.73 V for electropolymerization whereas both 4,4‘-bisT34bT and 6,6‘-bisT34bT have peak oxidation potentials for polymerization at 0.49 and 0.53 V (0.44 V vs NHE), respectively. For comparison, thieno[3,4-b]thiophene (T34bT) polymerizes with an oxidation peak at 0.9 V. Conjugated T34bT polymers prepared from T34bT, 4,4‘-bisT34bT, and 6,6‘-bisT34bT exhibit similar redox behavior showing oxidation and reduction peaks located at ca. 0.1 V and ca. −0.3 V, respectively, and optical band gaps of ca. 0.9 eV (1377 nm), whereas the conjugated polymer from 2,2‘-bisT34bT has redox peaks centered at 0.5 and 0.4 V. Like PT34bT prepared from T34bT, both PT34bTs prepared from 4,4‘-bisT34bT and 6,6‘-bisT34bT are pale blue to colorless in their oxidized states and sky blue in their neutral forms. PT34bT prepared from 2,2‘-bisT34bT is brown in the oxidized state. The conductivities of the PT34bTs from both 4,4‘- and 6,6-bisT34bTs were found to be ca. 2 × 10-5 S/cm in the undoped state, increasing to 0.2 S/cm after iodine doping. The conductivity of PT34bT from 2,2‘-bisT34bT was 2 × 10-5 and 0.007 S/cm in the neutral and oxidized forms, respectively.

A comparative study of the effect of fluorine substitution on the photovoltaic performance of benzothiadiazole-based copolymers

“…However, adding electron-withdrawing groups to the polymer can generally lower the energetic position of the LUMO level. [22][23][24] Among the numerous reported donor units, a benzo[1,2-b:4,5-b 0 ]dithiophene (BDT) skeleton has been widely applied as a donor unit in D-A type polymers by virtue of its highly planar nature. [8][9][10][11][12][13][14][15][16][17][18][19][20] Due to the strong electronwithdrawing characteristic of the uorine atom, the introduction of F as a substituent to the conjugated polymer would lower both energetic positions of the HOMO and LUMO levels of the synthesized polymer, as demonstrated by Brédas et al in a theoretical study.…”

Functional Oligothiophenes: Molecular Design for Multidimensional Nanoarchitectures and Their Applications

“…60, and 6,6′-bis(thieno[3,4-b]thiophene) 3.61 were synthesized and electrochemically polymerized by Sotzing et al (Chart 3.13) 529. Due to the extended π-conjugation, these dimers had lowered oxidation potentials in comparison to the monomer 3.54 (∆E ) 0.17-0.41 eV).…”

Fused Thiophenes and Some Oligomers and Polymers Therefrom

“…The reaction of 2,5-dibromothieno [3,2-b]thiophene (56) (easily prepared from TT (1) using two equivalents of NBS) with tributyl(thien-2-yl)stannane (57) in a Stille cross-coupling protocol resulted in the formation of 2,5-di(thien-2-yl)thieno [3,2-b]thiophene (58). The successive treatment of 58 with n-BuLi and Bu 3 SnCl gave (59), which was Stille cross-coupled to obtain 2,5-bis(5-phenylthien-2-yl)thieno [3,2-b] (67) were prepared from 2,5-dibromo-TT (56), through Suzuki and Stille cross-couplings, respectively (Scheme 17) [37].…”